WASHINGTON (USA Today) -- Democrat Daniel Inouye, the U.S. Senate's most senior member and a Medal of Honor recipient for his bravery during World War II, has died. He was 88.

He died of respiratory complications, according to the Associated Press.

As president pro tempore of the Senate, Inouye was third in line of presidential succession -- after Vice President Biden and House Speaker John Boehner. First elected to the Senate in 1962, Inouye's tenure is second only to Democrat Robert Byrd of West Virginia.

Perhaps more than any other politician, Inouye has been a dominating presence in Hawaii's history. He has represented Hawaii continuously since it achieved statehood in 1959, first in the U.S. House and then in the U.S. Senate, where he used his seat on the powerful Appropriations Committee to send federal dollars back home for a host of projects. Inouye has served on the commitee since 1971, and became chairman in 2009.

Inouye was a proud supporter of "earmarks," the special pet projects of senators, which were banned in the Senate in 2010. Inouye won approval for $392.4 million in earmarks in fiscal 2010, according to the non-partisan Center for Responsive Politics.

Throughout his life, Inouye was a witness to some of the nation's most historic moments, first as a teen-aged Red Cross volunteer who tended to the wounded when the Japanese attacked Pearl Harbor. He was keynote speaker at the tumultuous 1968 Democratic National Convention in Chicago.

Inouye would later serve as a member of the Senate committee investigating the Watergate scandal in the 1970s and chairman in the 1980s of the panel investigating the Reagan administration's sale of arms to Iran, whose proceeds were used to fund Nicraguan rebels in what became known as the Iran-Contra affair.

Yet it was on the battlefields in Europe during World War II where Inouye first earned distinction. At a time when the federal government placed thousands of Japanese Americans into relocation camps, Inouye and his Asian-American peers petitioned the White House for the right to serve in the military. He dropped out of school to join the Army's 442nd Regimental Combat Team, made up of second-generation Japanese-Americans known as Nisei.

In 1944, Inouye narrowly avoided death in France when a bullet struck him in the chest and hit two silver dollars he carried in his shirt pocket for good luck. He was awarded the Distinguished Service Cross in 1945 for his heroism in 1945 during a battle in Italy near the town of Terenzo. Inouye and his unit were pinned down by fire. Already wounded by a bullet to his mid-section, Inouye was lobbing hand grenades at the enemy when his right arm was almost completely severed by an enemy grenade launcher.

With his left arm, Inouye reached over to pry the live grenade out of his debilitated arm. Hours later while receiving treatment at an Army hospital, Inouye's right arm was amputated. During his recovery in the hospital, Inouye became friends with a fellow American soldier named Bob Dole -- who later became a U.S. senator from Kansas. Inouye and Dole would often work together on issues when Dole was Senate Republican leader.

More than a half-century after the battle at Terenzo, President Bill Clinton awarded Inouye and 21 other Japanese-American soldiers the Medal of Honor, the nation's highest civilian honor. At the ceremony in 2000, Clinton said the nation owes "an unrepayable debt" to Inouye and his fellow soldiers. "Rarely has a nation been so well-served by a people it ill-treated," Clinton said.

Inouye won election to a ninth Senate term in 2010 with 75% of the vote.

He is survived by his wife, Irene, a son, Ken, and a granddaughter named Maggie. Inouye's first wife, Margaret, died in 2006.